7.10  Neuro-Ophthalmic Differential Diagnoses and Aetiologies

• Bi-nasal Hemianopia
• Centrocaecal Scotoma (Bilateral)
• Chiasmal Disease
• Gaze Palsies
• Idiopathic Intracranial Hypertension (Pseudotumour cerebri) – Mimics to Exclude
• Light-Near Dissociation
• Miosis
• Mydriasis
• Myasthenia Gravis
• Non-Arteritic Anterior Ischaemic Optic Neuropathy - NAION (Risk Factors)
• Optic Atrophy
• Optic Disc Cupping
• Optic Disc Swelling
• Optic Disc Swelling (Bilateral)
• Optic Neuropathy (Causes)

1. Dermatochalasis
2. Tilted discs, Optic disc drusen
3. Bilateral sectoral retinitis pigmentosa, temporal retinoschisis, vigabatrin toxicity
4. Chronic raised intra-cranial pressure
5. Syphilis
6. Compression of lateral optic nerve / chiasm by an ICA aneurysm

“THONG”

• Toxic
  • Alcohol
• Hereditary
  • Leber’s hereditary optic neuropathy
• Optic neuritis
• Nutritional
  • Vitamin B12 deficiency
• Glaucoma
  • Acute angle closure glaucoma

1. Neoplasia
   
   1. Pituitary macroadenoma
      
   2. Craniopharyngioma
      1. Children: Dwarfism, delayed sexual development, obesity
      2. Adults: Visual loss
   3. Meningioma
      1. Tuberculum sellae, sphenoidal ridge
   4. Glioma
2. Vascular
   1. Aneurysm
   2. CVA
3. Cystic
   1. Sinus mucocele
4. Inflammatory
   1. Multiple sclerosis

In most supranuclear motility disease saccades are affected first, then pursuit, then the vestibulo-ocular reflex.

• Horizontal eye movements
  • Frontal Eye Fields: Generates horizontal saccade to the opposite side
  • Occipital: Generates horizontal pursuit to the same side
  • PPRF: Enacts horizontal gaze to the same side
  • (Ipsilateral CNVI, Contralateral CNIII)
• Vertical eye movements
  • Generated from the Rostral Interstitial Nucleus of the MLF (riMLF, midbrain) and the Interstitial Nucleus of Cajal (INC)

1. CVA
2. Tumour
3. MS
4. Infection (encephalitis)
5. Trauma
6. Hydrocephalus
7. Drugs
8. Conditions causing vertical gaze palsies:
   1. Parinaud’s (dorsal midbrain) syndrome
      1. Young male: Pinealoma, Craniopharyngioma
      2. Young female: MS
      3. Elderly: CVA
9. Progressive Supranuclear palsy (Steele-Richardson-Olszewski)

• Diseases
  • Chronic lung disease / Obstructive sleep apnoea, anaemia, renal failure, hypothyroidism, Addison’s disease
• Drugs “OATS”
  • Oral contraceptive pill (causes weight gain and dural venous thrombosis)
  • Vitamin A (e.g. acne cream)
  • Tetracyclines
  • Steroids (esp. withdrawal), Cyclosporine

“ABCD”

• Adie’s tonic pupil, Argyll-Robertson pupil
• Bilateral severe loss afferent light input into BE (retinas, ONs, chiasm)
• CN III aberrant regeneration
• Dorsal midbrain syndrome, myotonic dystrophy, diabetes

Anisocoria worse in dark – ‘4 P”

• Pancoast tumour (Horners)
• ****Prostitute (Argyll Robertson pupil)
• Pilocarpine
• Posterior synechiae
• (Old Adie’s pupil)

Anisocoria worse in light – “4 T”s

• Tonic pupil
• Third nerve palsy
• Tropicamide (dilating drops)
• Trauma

1. Mitochondrial encephalomyopathies (CPEO, Kearns-Sayre, MELAS)
2. Oculopharyngeal dystrophy (AD)
3. Thyroid eye disease
4. CN palsy
5. Other causes of ptosis

Miller Fisher Syndrome (Variant of Guillain-Barré Syndrome)

• Triad: Ophthalmoplegia + Ataxia + Areflexia.
• Anti-ganglioside complex antibodies (Anti-GQ1b), ↑ CSF protein

Myotonic Dystrophy

• Diplopia rare, no fatigue / diurnal variation
• Myotonic handshake
• Christmas tree cataracts
• Frontal balding

Eaton-Lambert Myasthenic Syndrome

• Ocular / bulbar involvement rare except for ptosis
• Muscle strength increases after exercise

Botulinum

• Dilated pupils (doesn’t occur in MG)

“Disc at risk” (small cup) +

1. Old age
2. Atherosclerosis
   1. Hypertension
   2. Nocturnal hypotension (often on awakening)
   3. Hypercholesterolaemia
   4. Diabetes
   5. Smoking
   6. Obesity
3. Obstructive sleep apnea
4. Anaemia
5. Vasculitis
6. Hyperviscosity
7. Thrombophilia
8. Drugs
   1. Sildenafil
   2. Amiodarone
9. Cataract surgery
   1. Performing cataract surgery when the fellow eye has already had an NAION has an absolute risk of around 50% of causing an NAION in the operated eye
   2. The risk of NAION being caused by cataract surgery in an eye that is “at risk” (but with no history of NAION in the fellow eye) is unclear
10. Optic disc drusen

1. Optic disc drusen
2. Pseudophakia
3. Myelinated nerve fibre layer
4. Optic nerve hypoplasia, disc pit

“ATROPHIC M”

• Advanced glaucoma
• Traumatic, toxic
• Radiation, retinal
• Optic neuritis (demyelinating, infectious, inflammatory, infiltrative)
• Papilloedema, paraneoplastic
• Hereditary
• Ischaemic
• Compressive
• Metabolic (DM, MPS)